Do 5th gens deal with crappy injectors like 4th gens clog up?

I've been having an increasingly rough idle/vibration for the last 30k miles on my '00. Minor loss of power, but engine operates pretty well at cruising speeds.

It's not a single completely dead cylinder. I've done the usual unplug coil to see if something changes.

Compression all 195ish.

It's not MAF, It's not coils or plugs. Those have all been replaced. It's not the cats. Precats are gone and the main cat is in very nice shape.

Exhaust smells "off" but can't tell if it's lean or rich. No codes except both B1S2 and B2S2 codes. P0420 and 0430 I think for the gutted precats.

Now it's getting to the point that on some starts, it stumbles around and misfires a bit and then "smooths out" to its normal vibrating idle.

Fuel pump and filter also replaced.

Have not checked regulator. Also hear slight hiss coming from somewhere near back of intake just past throttle body, but not sure how to test/find any leaks.

 

Just asking...does the stumbles after start only happen on hot/warm start?

 

Consider a can of bg44k fuel system treatment. Ive used it 2-3x now, about 1x annually. No ill effects notuced and should help to clean things up.

It did wonders on a van I had with a bad injector. Ran terrible with one(or more) injector apparently a problem. Took care if it quickly.

 

Thanks for the tip on the bg44k

It's more-so on cold starts, but I've had it do it maybe 10-20% of the time on hot starts.

All coils are genuine Hitachi. OEM MAF, etc. I did everything right when chasing it down but this is pretty much my last "maybe" before I get to timing jumping a tooth or chain slack. I hear an audible clatter from front bank near the water pump, but it's subtle.